The present disclosure relates to a power feeding unit, a power receiving unit, and a feed system that wirelessly supply power.
In recent years, a feed system performing wireless power feeding (also called wireless power transfer, contact free, or non-contact power feeding) on consumer electronics devices (CE devices) such as mobile phones and portable music players has attracted attention. In such a feed system, for example, a mobile phone (a power receiving unit) may be charged when the mobile phone is placed on a feeding tray (a power feeding unit). In other words, in such a feed system, the power feeding is allowed to be performed without connecting the power feeding unit and the power receiving unit by a cable or the like. Examples of the method of performing such wireless power feeding may include, for example, a magnetic field coupling method such as an electromagnetic induction method, an electric field coupling method, and an electromagnetic wave transmission method. Among them, the electric field coupling method is advantageously less in heat generation, less in leakage of electromagnetic field, and capable of reducing a thickness of a device.
In such a feed system, typically, for example, power transmission efficiency and the like are varied depending on arrangement position of the power receiving unit on a feeding surface of the power feeding unit at the time of power feeding. Specifically, a desirable range of the arrangement position of the power receiving unit exists on the feeding surface of the power feeding unit. For example, in Japanese Unexamined Patent Application Publication No. 2012-213322, an electric field coupling feed system in which a magnet is provided on each of a power feeding unit and a power receiving unit, and these magnets attract to each other to perform positioning is disclosed. In the feed system, for example, the power feeding unit is provided with a magnetic sensor, the power receiving unit is authenticated by determining whether a magnetic flux density exceeds a predetermined magnetic flux density, and the feeding operation is controlled based on the authentication result.
Incidentally, there is a feed system capable of performing wireless communication between the power feeding unit and the power receiving unit in addition to wireless power feeding. For example, in Japanese Unexamined Patent Application Publication No. 2013-9235, a communication unit that has a coil for wireless power feeding and an electrode for wires communication, and is capable of performing power feeding and data transfer without cable at a time is disclosed.